As a windmill for wind power generation, such a type of windmill is known that it has a horizontal rotation axis rotatively on the top of a supporting post, and the front edge of the rotation axis is provided with plural blades of a propeller shape. The other type of windmill is also known that it has a vertical rotation axis provided with plural longitudinal blades of a radial shape. These types of windmill have high power generation efficiency when they are jumboized because they receive a larger wind force.
However, merely jomboizing makes it difficult to support its own weight, and the own weight increases rotational resistance causing difficulties in practical application. Accordingly, conventional windmills have a limit of the power generation capacity up to 3000 kw. This invention is directed to provide a windmill less affected by the own weight and having high stability of rotation even in jumboized windmills.